Switch



Feb. 21, 1939. N. c. SC-HELLENGER SWITCH Filed June 3, 1935 IN VENTOR.

NEwTaM 6. SK/L/IFLLENGEE. %%afw Patented Feb. 21, 1939 UNITED STATES PATENT. OFFICE Chicago Telephone Su pply 00., Elkhart, Ind., a corporation 01' Indiana Application June 3, 1935, Serial No. 24,752

3 Claims.

This invention relates to a new and improved switch and more particularly to a switch especially adapted for association with a variable high resistance for joint operation to control a 5 circuit or circuits in a radio receiver, sound amplifier or similar apparatus.

Apparatus of this character as now usually designed and constructed are operated by the usual 110 volt commercial current and a switch is required which will handle safely and properly a current of this voltage at severalamperes. In circuits of types used in such apparatus it is highlyimportant that the switch not only have low resistance contacts but that the contact resistance remain substantially constant during long continued operation of the switch. It istherefore important that the contacts be initially of low resistance and that means be provided for maintaining such characteristics. To this 20 end the switch should have a fast break to minimize arcing and should havecontact wiping action.

, u able by a driving movement through a relatively shortarc. Radio receiving sets and sound amplifying equipment are now being made in very compact form and the dimensions of all their components must be correspondingly reduced.

, With a small switch combined with a small variable resistance the effective lever arm is small and consequently the operating torque must be small to permit easy operation with usual types of control knobs. Also with small variable resistances the effective length of the resistance is small and consequently it is important touse as small a portion of the movement of the movable contact as is possible for switch. actuation.

It is an object of the present invention to provide a new and improved switch and combination switch and variable high resistance.

It is a further object to provide a compact switch with a snap or toggle action and a positive contact separation independent of the. snap action.

It is also an object to provide a toggle switch in which the toggle is supported and connected independently of the switch arm.

It is an additional object to provide a switch 50 having means coacting with contact springs to" maintain the parts in fixed relation with the switch in the ofi position.

It is a further object to provide a switch with non-conducting contact wiping means operated ll during the actuation of the switch.

It is also an object to provide a'switch adapted to be mounted upon a flat base of insulating material.

It is an additional object to provide a switch to which the actuating force may be applied at 5 a point adjacent the periphery of the switch mounting.

It is a further object to provide a new and improved contact rivet or the like.

It is another object to provide a switch with 10 a new and improved switch contact with selflocating and tensioning portions.

It is also an object to provide a fixed contact located and positioned within a flat switch supporting base. 16

It is an additional object to provide a switch associated with a compact variable high resistance and operable'by a small arcuate movement of the variable resistance actuating means.

It is a further object to provide means for 20 jointly mounting such a switch and variable high resistance.

Other and further objects will appear as the description proceeds.

I have shown certain prefered embodiments of my invention in the accompanying drawing, in which--- 7 Figure 1 is a plan view of the switch with one of the spring contacts broken away and with the actuating cam and switch arm at their clockwise limit of movement;

Figure 2 is a view similar to Figure 1 but showing the actuating cam in an intermediate position;

Figure 3 is a view similar to Figures 1 and 2 but showing the actuating cam and switch arm at their counterclockwise limit of movement;

Figure 4 is a verticalsection taken through the switch on line 4-4 of Figure 2;

Figure 5 is a view of Figure 1 as seen from below;

Figure 6 is a view, partly broken away, of the switch assembled in a housing and mounted to be actuated Jointly with a variable high resistance;

Figure 7 is a fragmentary section taken on line |-"l of Figure 1-, showing a non-conducting raised portion on the switch arm;

Figure 8 is a fragmentary section showing the spring and fixed contacts;

Figure 9 is a section similar to Figure 8 but showing the movable contact engaging the spring and fixed contacts;

Figure 10 is a fragmentary section taken on line l0lll of Figure 5; e

Figure 11 is a fragmentary section on an enlarged scale showing a contact rivet before deformation;

Figure 12 is aview similar to Figure 11 but showing the rivet after deformation; and

Figure 13 is a perspective view of the actuating cam.

The switch comprises the base l5 which in the form shown is a. flat disc having the locating notches l6 formed in its periphery. This base will normally be formed of nonconducting materials such as sheet fibre, Bakelite or other syn thetic resinous material. The pivot I1 is secured to the base by riveting over its lower end l3 as shown in Figure 4. This pivot member preferably has an enlarged shoulder l9 which serves as a seat for the pivot arm 20. The shoulder I9 is on or off position.

preferably of a thickness equivalent to the height of the exposed ends of the'contact rivets 2| so that the switch arm is maintained parallel with the base member IS. The pivot I1 is formed with an intermediate shoulder 23 which serves as a pivot for the arm 20 and as a seat for the lower portion 24 of the actuating cam. The various parts are held in place by the enlarged head 26 of the pivot I! which head is formed after the parts are assembled on the pivot.

The form of switch shown is a double pole, single throw switch, although it will be readily apparent that the various elements of the construction may be adapted to single pole, single throw, single pole, double throw and double pole, double throw switches without material modification.

The switch arm 2|] in the form shown carries a pair of contact members 2| which comprise rivets as shown in detail in Figures 11 and 12. The undeformed rivet shown in Figure 11 has a rounded contact face 2'! surrounded by a shoulder 28 and a second contact face 29 surrounded by shoulder 30. When the rivet is deformed to clamp it to the switch arm, the shoulder 30 is deformed as shown in Figure 12, but the faces 21 and 29 are entirely undeformed. This swaging operation may be carried out by the means of tubular swaging elements which engage the shoulders 28 and 30 but do not contact the faces 21 and 29. This will leave the contact faces 21 and 29 with unbroken surfaces which will aid materially in effecting low resistance contacts. Rivets of this type having silver plating or other low resistance plating on their contact ends may be assembled by a circular swaging punch without injuring the low resistance surfaces.

The switch arm 20 is preferably formed of sheet material similar to that of which the base I5 is formed. It maybe formed by stamping from sheet material and the non-conducting raised portion 3| shown in detail in Figure '7 may be pressed from the sheet material during the stamping operation. These raised portions 3| are also clearly shown in Figures 1 to 3 and it will be apparent that when the switch is in the of! position as shown in Figure 3, these non-conducting portions 3| will engage the spring contact portions 32 of the contact springs 33. These portions 3| by engaging the springs in the off position of the single throw switch, such as that shown, will prevent any looseness of the switch arm in that position. The contacts 2| engage the face of the base l5 or the fixed contacts supported thereby throughout the operation and in either By means of the extrusions 3| the spring contacts 33 serve to act as restraining forces urging the switch arm toward the base and prevent this function of holding the arm down, also exert a cleaning action on the contacting surface of these upper contact springs 3| and serve to keep them clean and free from foreign matter or from products of the arcs which occur when the switch contacts are separated. The extrusions 3| may serve to apply a small amount of lubricant to the contacts.

The spring contacts 33 are shown in detail in Figures 8 and 9. They include end portions which are held to the base I5 by rivets 34, and also connecting or soldering lugs 35 which extend to the outer face of the base through slots as shown in Figure 5. The spring contact members 33 include an intermediate portion 38 which extends at an acute angle away from the base l5 and which portion joins a re-entrant angular portion 31 which normally extends down to and in contact with the base 15, as best shown in Figure 8. The contact portion 32 extends beyond the re-entrant portion 31 and in a plane substantially parallel with the base IE, but with its ends rounded upwardly to ride over the contact rivets 2| as clearly shown in Figures 8 and 9. It will be apparent that the re-entrant portion 31 by normal contact with the base maintains these springs normally flexed a fixed amount. Their additional flexure is that caused by the thickness of the rivet 2| as clearly shown in Figure 9.

The re-entrant portion 31 which strikes the base is in close proximity to the contacting portion 32 and the principal spring action is between the portion 3'! and the securing rivet 34. This construction greatly simplifies the forming operation of making the springs and also their uniform assembly on the base. This construction maintains an accurate minimum distance between the contact surface 32 of the flexible spring and the contact surface 38 of the fixed contact member 39. When the contact rivet 2| moves between the two contact surfaces 32 and 38 the portion of the flexible contact which bears against the base is raised from the base and the full pressure of the spring is exerted against the contact rivet. This construction accurately positions the flexible contact spring at the correct height above its associated stationary contact and prevents any tendency of the contact portion 32 of the spring 33 being too close to the switch base. If it were too close to the switch base this would result in the contact rivet not riding in under the spring properly and in the contacting spring riding on the am after the contact rivet had moved away. Either of these conditions would materially hinder the switch action.

The stationary contact members 39 and their contact portions 38 fit into perforations 40 formed in the base member I5. These contact portions are substantially in the plane of the inner face of the base member l5, as clearly shown in Figures 8 to 10. The contact members 39 are formed wit intermediate portions 4| which extend at righ angles to the portions 33 through the perforations 43, and with outer portions substantially parallel to the portions 38 and secured to the outer face of the base member I5 by means of rivets 42. The contacts 38 are also preferably formed with integral connecting lugs 43 so as to avoid the necessity of additional connections. By having the contact face 33 flush with the surface of the base on which the contact rivet travels, there is no tendency for the switch arm 23 to move out of its normal plane of rotation and consequently no tendency for it to bounce and cause an are as the switch makes contacts, which tendency would create a very undesirable condition and rapidly shorten the life of the switch.

The actuating cam is shown in perspective in Figure '13 and comprises a lower portion 24 and an upper portion 25 which have separate bearings on thapivot i1. These portions 24 and 25 are preferably integrally connected by the lateral portion 44. The lower portion 24 is provided with the downwardly extending lug 45 which, as shown in Figures 1 to 4, fits in a notch or opening 46 formed in the end of the switch arm opposite to that on which occurs the contact rivets 2|. It will be noted that this opening or recess 46 is materially greater in size than the lug 45. The purpose of this size relationship will be explained hereaftenll The portion 24 of the cam also carries the 1gpwardly extending T-head 41- upon which is 49. The opposite end of the pitman 49 passes through a. perforation formed in the stop member 58, this member having downwardly extending lugs 5| which are clamped against the under side of the base l5 to rigidly secure the stop member in position on the base. The coil spring 52 is carried by the pitman 49 and engages the stop member and the shoulder at the perforated end 48 of the pitman.

The upper portion 25 of the cam is provided with a slot 53 to receive a drive pin, such as shown at 54 of Figure 6, and indicated in section at 54 in Figures 1, 2 and 3. It will be noted that this :slot 53 is also materially larger than the pin 54,; This switch arm 28 is provided with shoulders 55 and.56 which are adapted to engage the stop member 58' at the limits of counterclockwise and clockwise movement respectively.

It will be apparent from examination of Figure 4 that the pitman spring and actuating cam portion 24 are all spaced from the contact arm 20 so that they do not give any thrust to that arm. The actuating thrust to the arm 28 is transmitted solely through the downwardly extending lug 45 and this lug is so designed as to exert a thrust only in the direction of operating movement. This avoids any high frictional thrust against the pivot and between the contact rivets and the base which thrusts occur'when the pitman is secured in the switch arm in former types of construction.

The switch is shown as assembled in a tubular housing in Figure 6. The housing 51 is secured to the base 58 of a variable high resistance by means of the locating fingers 59 and the downturned clamping lugs 60. The base 58 carries a resistance member 6|, and a contact member 62 is movable over the resistance by the rotatable arm 63 which is actuated by the shaft 64 extending through the thimble 65. The disc is also rotated by the shaft 64 and carries the drive pin 54 which coacts with the notch 53 in the switch operating cam. The tubular housing 51 is formed with the inturned flange 61 which has downturned portions 68 fitting in the locating notches IS in the base member I5. The inwardly bent fingers 69 formed from the housing 51 engage the inner surface of the base i5 and positively hold it in place. These fingers'fiflmay be resilient and have a spring action so that the base may be forced beyond them. The fingers 69 will spring out when the base is forced beyond them and will positively hold the base in place. The disc 66 may be formed of non-conducting material tted the slotted end 48 of the'pitman 'terclockwise movement of the cam 24.

and simply serve as insulation between the switch and variable high resistance. It may, however,

be formed of conducting material and serve as a shield between the switch and variable high resistance, being grounded if desired, Since the actuating cam 24 does not carry current it is unnecessary to make the drive pin 54 of nonconducting material when the disc 66 is conducting and serves as a shield, although the pin may be made of such material if desired.

In the operation of my improved switch with the parts in the position shown in Figure 1, the contact rivets 2| are in engagement with their respective spring and fixed contacts and both of the circuits are closed. In order to open the cir- This is accomplished by the movement of the drive pin 54 which is shown in Figure 1 as just entering the slot 53. The progress of movement of the drive is indicated in Figure 2. The drive pin 54 engages the right-hand edge of the notch 53 as seen in these figures, and begins the coun- This movement swings the pitman 49 past its center position as shown in Figure 2, and also brings the lug 45 against the edge of the notch 46 in the end of the contact arm 20. Its engagement against this edge of the notch causes thelug 45 to positively start counterclockwise movement of theswitch arm 20. If the contacts on the arm and their associated spring and fixed contacts are smooth and'clean, movement of the arm 20 may be initiated by the action of the, spring 52 against the stop 50 and enlarged end 48 of the pitman 49. The toggle action may cause the cam 24 to move faster than the drive pin 54 so that the lug 45 engages the wall of notch 46 under the force of the toggle spring. A momentum will be acquired by the spring 52 moving the cam faster than the drive pin moves it and as soon as the pitman passes center the spring snaps the lug 45 against the wall of notch 46. This spring action will then complete the movement, swinging the parts to the position shown in Figure 3 where the switch contacts 32 ride on the non-conducting extrusions If, however, the contact surfaces are rough or a weld has been formed, the lug 45, by its engagement with the edge of notch 46 under the direct thrust upon the cam 24 by the drive pin 54, will positively break the weld and start the movement of the switch arm, which movement will then be completed as a snap action by means of the spring toggle construction. The notch or opening 53 is made sufficiently large so that the break away of the switch arm contact from the fixed and spring contacts will be a snap action regardless of the speed of movement of the drive pin 54. This movement can be completed before the rear end of the notch 53 engages the drive pin 54. The size of the notch 46 is important and, as will be readily apparent from an inspecand spring contacts, if they tend to stick together sufliciently to fail to be separated by the mediately adjacent the bearings or intermediate the bearings. The thrust transmitted by lug 45 is in a plane adjacent a bearing, the thrust transmitted by drive pin 54 is in the plane of a bearing, and the toggle thrust through the portion l1 is in a plane intermediate the bearings. Consequently there is free action of the operating member which is positively supported on these spaced bearings.

An important distinguishing feature of the construction shown is the fact that the operating fork or notch 53 on the cam is located outside of the pivot of the cam, or on the opposite side of the pivot from the contacts on the switch arm. This makes it possible to attain quite a long operating radius for the drive pin on even a small size switch. The long operating radius means that the switch operation requires a relatively small arc of volume control rotation when comvbined with a variable high resistance, as shown in Figure 6. This is true even though the diameter of the switch and control be quite small.

Another important feature of the switch design is that the switch arm is entirely free from any lateral or twisting thrust from the spring toggle. This toggle is supported entirely free from the switch arm.

While I have shown certain preferred embodiments of my invention, it is capable of modification and change to meet varying conditions and requirements, and I contemplate such changes and variations as come within the spirit and scope of the appended claims.

I claim:

1. A switch comprising a base, a pivot secured thereto, a stop secured thereto in spaced relation to the pivot, a switch arm rotatably mounted on said pivot, portions of the switch arm coacting with the stop to limit rotation of the switch arm, an operating cam rotatably mounted on said pivot and operatively connected to the switch arm, and resilient means connecting the stop and operating cam to urgethe cam towards limits oi its movement;

2. A switch comprising a base, a pivot secured thereto, a stop secured thereto in spaced relation to the pivot, a switch arm rotatably mounted on said pivot, portions of the switch arm coacting with the stop to limit rotation of the switch arm, an operating cam rotatably mounted on said pivot, means on the cam engaging the arm, and resilient means connecting the stop and cam to urge the cam and arm toward their limits of movement.

3. A switch comprising a base, a pivot secured thereto, a stop secured thereto in spaced relation to the pivot, a switch arm rotatably mounted on said pivot, portions of the switch arm coacting with the stop to limit rotation of the switch arm, an operating cam rotatably mounted on said pivot, a lug on the cam loosely fitting in an opening in the arm, a pitman connecting the cam and the stop, and a spring carried by the pitman and ward their limits of movement. g

' NEWTON C. SCHELIENGER.

' engaging the stop to thrust the cam and arm to- 

